I am on 4.3 with Knox 0x0, System status shows: Custom how do I change it to official without tripping Knox to 0x1?
Reroot it without tripping Knox, and Triangle Away.
Read extremely carefully.
And if you succeed, buy Chainfire a beer or something.
...you said you were 4.3 rooted without knox.
However, check this http://forum.xda-developers.com/show....php?t=2487916 out.